/* -*- mode: C -*-  */
/*
  Test suite for whether two vertices are connected by an edge.
  Copyright (C) 2011 Minh Van Nguyen <nguyenminh2@gmail.com>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc.,  51 Franklin Street, Fifth Floor, Boston, MA
  02110-1301 USA
*/

#include <igraph.h>
#include <stdio.h>
#include <time.h>

#define R_INTEGER(a,b) (igraph_rng_get_integer(igraph_rng_default(), (a), (b)))

/* Crash the library function here. We expect error codes to be returned here.
 */
int error_test() {
  igraph_t g;
  igraph_bool_t connected;
  igraph_integer_t nvert, u, v;
  int ret;

  igraph_rng_seed(igraph_rng_default(), time(0));
  igraph_small(&g, /*nvert*/ 0, IGRAPH_UNDIRECTED, 0,1, 1,2, 2,0, -1);
  nvert = igraph_vcount(&g);
  u = (igraph_integer_t)R_INTEGER(-100*nvert, 100*nvert);
  v = (igraph_integer_t)R_INTEGER(nvert, 100*nvert);

  igraph_set_error_handler(igraph_error_handler_ignore);
  ret = igraph_are_connected(&g, u, v, &connected);
  if (ret != IGRAPH_EINVVID) {
    printf("Error test failed.\n");
    return IGRAPH_FAILURE;
  }
  igraph_destroy(&g);

  return IGRAPH_SUCCESS;
}

/* Testing for two vertices being connected by an edge in various graphs.
 */
int connected_test() {
  igraph_t gcomplete, gempty;
  igraph_bool_t connected;
  igraph_integer_t nvert, u, v;

  igraph_rng_seed(igraph_rng_default(), time(0));

  /* A complete graph on n vertices. Any two distinct vertices are connected */
  /* by an edge. Hence we expect the test to return true for any given pair */
  /* of distinct vertices. */
  nvert = (igraph_integer_t)R_INTEGER(2, 100);
  igraph_full(&gcomplete, nvert, IGRAPH_UNDIRECTED, IGRAPH_NO_LOOPS);
  u = (igraph_integer_t)R_INTEGER(0, nvert - 1);
  do {
    v = (igraph_integer_t)R_INTEGER(0, nvert - 1);
  } while (v == u);
  igraph_are_connected(&gcomplete, u, v, &connected);
  if (!connected) {
    printf("Expected connected = true, but received connected = false.\n");
    return IGRAPH_FAILURE;
  }
  igraph_destroy(&gcomplete);

  /* A graph with n vertices, but no edges. Any two distinct vertices are */
  /* not joined by an edge. Thus we expect the test to return false for any */
  /* given pair of distinct vertices. */
  nvert = (igraph_integer_t)R_INTEGER(2, 100);
  igraph_empty(&gempty, nvert, IGRAPH_DIRECTED);
  u = (igraph_integer_t)R_INTEGER(0, nvert - 1);
  do {
    v = (igraph_integer_t)R_INTEGER(0, nvert - 1);
  } while (v == u);
  igraph_are_connected(&gempty, u, v, &connected);
  if (connected) {
    printf("Expected connected = false, but received connected = true.\n");
    return IGRAPH_FAILURE;
  }
  igraph_destroy(&gempty);

  return IGRAPH_SUCCESS;
}

int main() {
  int ret;

  ret = error_test();
  if (ret)
    return IGRAPH_FAILURE;
  ret = connected_test();
  if (ret)
    return IGRAPH_FAILURE;

  return IGRAPH_SUCCESS;
}
